Self modifying code, lambda calculus - Re: ENIAC programming

Johnny Billquist bqt at
Fri Sep 18 16:42:18 CDT 2015

On 2015-09-18 18:21, Jon Elson wrote:
> On 09/18/2015 08:45 AM, tony duell wrote:
>>>> As far as I know, the VAX11/730 (There is one next to me waiting for
>>>> me to have time
>>>> to restore it) has the microcode entirely in RAM. Classic PERQs (3
>>>> in the next room) have
>>> The PDP-11 console loads the microcode from disk then mostly just
>>> sits there
>>> looking pretty whilst the VAX runs.
>> The 11/780 has a PDP11 to load the microcode (I think) but the 11/730
>> makes do with an
>> 8085. After booting I think that handles the console port still.
>> -tony
> 780's had a board of fixed microcode, and then a WCS board was added in
> later revisions (and all machines in the field had to be upgraded) to
> add some additional code to handle added instructions used by the OS (at
> least for VMS, don't know if BSD used it).  The WCS microcode was in a
> file on the LSI-11's floppy, and it was called in at a certain point of
> the VMS boot sequence.  That caused a line to print during the boot.
> The typical dot matrix printer console on the 780 was also connected
> to/through the LSI-11.

The normal WCS option for the 11/780 was an option. Not everyone had it. 
Were there another option with some WCS that actually everybody had?


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